Remote sensing monitoring of grassland snow in China:From October 2007 to March 2008

Snow disaster is one of the main meteorological disasters in the grassland pasturing area of China in winter and spring.Based on the NASA MODIS data,remote sensing was used to monitor the grassland snow disaster in early 2008.The data of grassland snow was successfully obtained covering from October 15th,2007 to March 20th,2008 of nine provinces,including Inner Mongolia,Liaoning,Jilin,Heilongjiang,Sichuan,Tibet,Gansu,Qinghai and Xinjiang.It can provide complete,timely and exact science reference for the agriculture department to make decisions about disaster prevention and reduction.The results show:(1)For the absolute comparison of the grassland area in the nine provinces,during the whole monitoring period,the average snow area of grassland in Xinjiang is the largest,which is 291485 km2.The least is Liaoning,which is 2483 km2.In the period,the order of snow area of all the provinces is Xinjiang,Inner Mongolia,Tibet,Qinghai,Sichuan,Gansu,Heilongjiang,Jilin and Liaoning.(2)As the proportion of snow area of every province to its own total grassland area,in each phase of the period,Xinjiang has the largest proportion to the whole province's total grassland area,which is 38.15%.Liaoning's grassland snow area is the least,which is 3.04%.In each monitoring phase,every province grassland snow area to the total grassland area is ordered by Xinjiang,Qinghai,Sichuan,Gansu,Inner Mongolia,Heilongjiang,Tibet,Jilin and Liaoning.(3)During the monitoring time period,Qinghai-Tibet Plateau and Inner Mongolia are the core snowing areas,and there are fluctuations of snowing in the other areas.(4)Monitoring started from October 15th,2007,when fluctuations of grassland snow area existed,the total snow area increased.In the late January of 2008,the grassland snow area reached the maximum value,and then it tended to decrease.The total grassland snow area in the monitoring area reached the maximum value in the late January of 2008,which is 2251141 km2.(5)At the beginning of the monitoring period,10% of the grassland was covered by snow on average in every province.In the late January of 2008,the proportion of grassland snow area to the total grassland became 61.48% on average.At the end of monitoring period,which is mid-March,about a quarter of grassland was covered by snow in every province of the nine.